A processor such as a CPU (Central Processing Unit) which performs an arithmetic operation of a mathematical function generally uses a Taylor series operation when performing the arithmetic operation of an exponential function. In the arithmetic operation of the exponential function, in order to obtain sufficient precision when the Taylor series operation is truncated at a finite degree, it is necessary to decompose the exponential function into the Taylor series operation that is an arithmetic operation of a Taylor series converging in precision given at the finite degree and a coefficient.
In a conventional art, calculation processing of the coefficient before the execution of the Taylor series operation in the arithmetic operation of the exponential function is implemented by software, uses the combination of a plurality of sets of conventional instructions, and involves many data transfers between a floating-point register and an integer register and arithmetic processing using an integer arithmetic unit such as a bit operation and a shift operation. Therefore, processing the entire arithmetic operation of the exponential function requires many instructions, which deteriorates performance such as affecting instruction issuance throughput.
There has been proposed a processor capable of executing the Taylor series operation at a high speed by storing, in a dedicated memory, a set of coefficient tables storing coefficient data of a Taylor series operation of a mathematical function and reading the coefficient data necessary for the Taylor series operation directly from the coefficient table to supply the read coefficient data to a floating point product-sum arithmetic unit (for example, refer to Patent Literature 1). There has also been proposed a processor having dedicated trigonometric function operation auxiliary instructions as instructions for the execution of the decision of a Taylor series expansion function and the calculation processing of an input argument to the expansion function which are performed before the execution of a Taylor series operation of a trigonometric function (for example, refer to Patent Literature 2).
Patent Literature 1: Japanese Laid-open Patent Publication No. 2008-234076
Patent Literature 2: Japanese Laid-open Patent Publication No. 2011-13728